A breakwater is designed to oppose-alternate (by absorption or reflection or both) the energy of pounding waves, thus generating a protected, calm water activity zone or (in some utilizations) a land front mass protected from the erosive power of the sea, all that with the lowest possible cost and lowest environmental damage.
Conventional Breakwaters
                1. Fill-material based breakwaters are typically constructed from:                    sand and rock rubble mounds (the sizes of the rocks depend on the hydrodynamic conditions on site)            sloped revetment walls, with a concrete block crust, and land-rubble backing (supported by weighty concrete tetrapods or similar constructs)                        2. Caisson (vertical wall) breakwaters with fill material, to provide for mass and resistance against overturning.        3. Complementary caisson-rubble mound-revetment breakwaters in various functionally dictated combinations.        
The bathymetric conditions, the impacting wave energy and the availability of fill-materials are the deciding factors of the breakwaters' realization and their costs. Fill-material breakwaters, because of their geometric wide-base configuration, reach their techno economical limit with the water depth of about 20-25 meters, beyond which, with every additional meter of depth, the material quantities become a critical economic constraint.
Caisson (front or rear solution) technology is relatively expensive in shallow waters, but with the growing depth, the cost of the rubble mound or the revetment wall may outpace it considerably.
It should be borne in mind that the fill-material approach for breakwater construction, dredged or mined or excavated from nature and transported and deposited on site, is not just costly but also environmentally questionable-negative-destructive. Thus in many coastal conditions the fill-material approach (when considered on a large scale) is not a viable option.
An object is to provide improved wave-energy dissipating structures adapted for uses such as breakwaters, acoustic walls and heat exchangers.